Method for improving adhesion of polyurethane adhesive to polyester based laminate without surface preparation

Abstract

Disclosed is a composite laminate made from unsaturated polyester resin that can be bonded using polyurethane adhesive without secondary treatment of the composite laminate and with improved bond strength and failure mode. Also disclosed are methods of making such composite laminates.

What is claimed: 
     
         1 . An uncured resin composition comprising an unsaturated resin and an unsaturated monomer having a hydroxyl functional group. 
     
     
         2 . The resin composition of  claim 1  wherein the unsaturated resin is selected from at least one of unsaturated polyester resin and vinyl ester resin. 
     
     
         3 . The resin composition of  claim 1  wherein the unsaturated monomer having a hydroxyl functional group comprises a (meth)acrylic monomer having a hydroxyl functional group. 
     
     
         4 . The resin composition of  claim 1  wherein the unsaturated monomer having a hydroxyl functional group is selected from at least one of glycerol monomethacrylate; 2-hydroxy methacrylate; 2-hydroxyethyl acrylate (HEA); 2-hydroxyethyl methacrylate (HEMA); N-(2-hydroxypropyl)methacrylamide; 3-hydroxypropyl acrylate; hydroxypropyl methacrylate; hydroxyhexyl acrylate; hydroxyoctyl methacrylate; pentaerythritol triacrylate; poly(propylene glycol) monomethacrylate; poly(propyleneglycol) dimethacrylate; 4-methacryloxy-2- hydroxybenzophenone; poly(ethylene glycol)-monomethacrylate; poly(ethylene glycol)-dimethacrylate; poly(ethylene glycol)-diacrylate; poly(ethylene glycol)-monomethylether monomethacrylate. 
     
     
         5 . The resin composition of  claim 1  comprising a reactive aromatic diluent. 
     
     
         6 . The resin composition of  claim 1  comprising about 1 wt % to about 30 wt % of the unsaturated monomer having a hydroxyl functional group. 
     
     
         7 . The resin composition of  claim 1  comprising about 1 wt % to about 10 wt % of the unsaturated monomer having a hydroxyl functional group. 
     
     
         8 . A composite laminate comprising an exterior layer of cured reaction products of the resin composition of  claim 1  and reinforcement. 
     
     
         9 . A composite article comprising a first composite laminate comprising an exterior layer of cured reaction products of the resin composition of  claim 1  and reinforcement, the exterior layer being free of secondary treatment; the exterior layer bonded to a substrate surface by cured reaction products of a structural adhesive. 
     
     
         10 . The composite article of  claim 9  wherein the structural adhesive is a polyurethane adhesive. 
     
     
         11 . The composite article of  claim 9  wherein the substrate surface comprises a second composite laminate comprising an exterior layer of cured reaction products of the resin composition of  claim 1  and reinforcement. 
     
     
         12 . The composite article of  claim 9  wherein the substrate surface comprises a second composite laminate comprising an exterior layer of cured reaction products of the resin composition of  claim 1  and reinforcement, the second composite laminate exterior layer being free of secondary treatment. 
     
     
         13 . Use of about 1% to about 30% by weight of resin composition of an unsaturated monomer having a hydroxyl functional group in an unsaturated resin composition to improve bond strength of a composite laminate made using the unsaturated resin composition. 
     
     
         14 . A method of improving the bond strength of a composite article, comprising:
 adding about 1 wt % to about 30 wt % of an unsaturated monomer having a hydroxyl functional group to an unsaturated resin to form a resin composition;   preparing a composite laminate from the resin composition; and   bonding the composite laminate to a substrate with a structural adhesive;   wherein an exterior layer of the composite laminate without secondary treatment has a higher bond strength to the substrate than an exterior layer of a composite laminate prepared from the resin composition without the unsaturated monomer having a hydroxyl functional group and bonded to the same substrate.